Sudden cardiac death and dialysis patients

Dialysis patients have extraordinarily high mortality rates. The death rate for all US dialysis patients in 2004 was 230 per 1000 patient-years. Cardiac disease is the major cause of death in dialysis patients and accounts for 43% of all-cause mortality. In the United States Renal Data System database 62% of cardiac deaths (or 27% of all deaths) are attributable to arrhythmic mechanisms. The estimated rate of sudden cardiac death in US dialysis patients in 2002 was 7% per year. There are several plausible explanations for the special vulnerability of dialysis patients to sustaining sudden cardiac death. Obstructive coronary artery disease, coupled with diminished tolerance to myocardial ischemia (in the setting of myocardial fibrosis and left ventricular hypertrophy), rapid electrolyte shifts in hemodialysis patients, and derangements in autonomic function may all contribute to this heightened risk of sudden cardiac death. This review focuses on the epidemiology of sudden cardiac death in dialysis patients, underlying mechanisms of sudden death, and potential interventions to reduce the risk of sudden cardiac death in dialysis patients (including medical therapy and defibrillators). It is unlikely that one single therapeutic intervention will prevent sudden cardiac death in dialysis patients; but a more modest (and attainable) goal is the implementation of multiple strategies to reduce the risk of sudden cardiac death in this special high-risk population.     

Risk factors for non-fatal myocardial infarction and cardiac death in incident dialysis patients

Background. The risks of major cardiac events in patients initiatinglong-term dialysis related to prior coronary disease and variousother factors are not well known. Methods. We used United States Renal Data System data to analysethe outcomes of non-fatal myocardial infarction (MI) and cardiacdeath in incident dialysis patients from years 1997 through2001 (n = 214 890). The presence of established coronaryartery disease was determined from the Medical Evidence form,non-fatal MI events were determined from Medicare claims’data and cause of death was determined from the Death Notificationform. Multivariable analyses were performed employing Cox proportionalhazards models using demographics, co-morbidities, laboratoryvariables, prior erythropoietin use, body mass index and typeof dialysis. Results. In patients with prior coronary disease as comparedto those without, the adjusted relative risk of non-fatal MIwas 1.57 (95% CI, 1.5–1.65) and cardiac death was 1.16(95% CI, 1.14–1.18). The 5-year cumulative incidence ofnon-fatal MI was 8.1 and 6% and cardiac death was 48.3 and 40.2%,in patients with and without prior coronary disease, respectively.Amongst important factors, blacks had a lower risk of non-fatalMI and cardiac death as compared to whites. A history of hypertensionconferred a lower independent risk of cardiac death events.Lower haemoglobin, higher albumin and higher creatinine valueseach conferred a lower independent risk of non-fatal MI andcardiac death. Conclusions. Incident dialysis subjects with prior coronarydisease have a risk of non-fatal MI greater by 57% and cardiacdeath by 16% as compared to subjects without prior coronarydisease. In both populations, the competing risk of cardiacdeath is several-fold greater than that of non-fatal MI. Thereare several factors suggesting reverse epidemiology phenomenawith respect to major cardiac events in the dialysis population.     

Sudden death in chronic dialysis patients

Methods. Causes of sudden death were investigated in 113 chronic dialysis patients who died during the 10-year period from July 1979 to January 1989; post-mortem examination was performed on 93 of the cases (autopsy rate; 82.3%). Sudden death was regarded as death 24 h after the onset of acute illness in patients without any restriction in their daily activities. There were 35 sudden death cases out of the 93 autopsied chronic dialysis patients. We analysed the causes of sudden death for all chronic dialysis patients and for those who died suddenly. Results. The mean age of the 93 cases was 61.4 ± 10.5 years (±SD). Stroke was the most frequent cause of death (24 cases, 25.8%) in the 93 autopsied cases. This was followed by cardiac disease in 18 (19.4%), infectious disease in 16 (17.2%), malignancy in 14 (15.1%), and dissecting aortic aneurysm in 5 (5.4%). The mean age of the 35 sudden death cases was 60.9 ± 10.9 years. Of the 35 sudden death cases in chronic dialysis patients, dissecting aortic aneurysm was the most common cause of sudden death (5 cases, 14.3%), followed by cerebral haemorrhage in three (8.6%), acute subdural haematoma in three (8.6%), acute myocardial infarction in two (5.7%), cerebral infarction in two (5.7%), and subarachnoidal haemorrhage in one (2.9%). Conclusions. Dissecting aortic aneurysm, leading frequently to stroke as a cause of sudden death in chronic dialysis patients, at least in Japan, should be carefully differentiated from other cardiac disease in chronic dialysis patients, such as severe atherosclerosis.     

Sudden and cardiac death rates in hemodialysis patients

BACKGROUND: Sudden and cardiac death (including death from congestive heart failure, myocardial infarction, and sudden death) are common occurrences in hemodialysis patients. The intermittent nature of hemodialysis may lead to an uneven distribution of sudden and cardiac death throughout the week. The purpose of this study was to assess the septadian rhythm of sudden and cardiac death in hemodialysis patients. METHODS: Data from the United States Renal Data System (USRDS) were obtained to examine the day of death for United States hemodialysis and peritoneal dialysis patients from 1977 through 1997. The days of death were also determined for patients in the Case Mix Adequacy Study of the USRDS. RESULTS: There was an even distribution of sudden and cardiac deaths for patients on peritoneal dialysis, and hemodialysis patients dying of noncardiac deaths also had an even distribution. For all hemodialysis patients, Monday and Tuesday were the most common days of sudden and cardiac death. For patients in the Case Mix Adequacy Study designated as Monday, Wednesday, and Friday dialysis patients, 20.8% of sudden deaths occurred on Monday compared with the 14.3% expected (P = 0.002). Similarly, 20.2% of cardiac deaths occurred on Monday compared with the 14.3% expected (P = 0.0005). Similar trends were found on Tuesday for Tuesday, Thursday, and Saturday dialysis patients. CONCLUSIONS: The intermittent nature of hemodialysis may contribute to an increased sudden and cardiac death rate on Monday and Tuesday for patients enrolled in the USRDS.     

Sudden cardiac death in haemodialysis patients: Preventative options

Sudden cardiac death (SCD) is the most common cause of death in haemodialysis patients, accounting for 25% of all‐cause mortality. There are many potential pathological precipitants as most patients with end‐stage renal disease have structurally or functionally abnormal hearts. For example, at initiation of dialysis, 74% of patients have left ventricular hypertrophy. The pathophysiological and metabolic milieu of patients with end‐stage renal disease, allied to the regular stresses of dialysis, may provide the trigger to a fatal cardiac event. Prevention of SCD can be seen as a legitimate target to improve survival in this patient group. In the general population, this is most effective by reducing the burden of ischaemic heart disease. However, the aetiology of SCD in haemodialysis patients appears to be different, with myocardial fibrosis, vascular calcification and autonomic dysfunction implicated as possible causes. Thus, the range of therapies is different to the general population. There are potential preventative measures emerging as our understanding of the underlying mechanisms progresses. This article aims to review the evidence for therapies to prevent SCD effective in the general population when applied to dialysis patients, as well as promising new treatments specific to this population group.     

Treatment of cardiac arrhythmias in patients with acute myocardial infarction

Cardiac arrhythmias and conduction disturbances are commonly observed in patients with acute myocardial infarction. The available data suggest the administration of prophylactic lidocaine, either through a large intramuscular dose (300 mg), which is particularly suited for out-patient situations, or through intravenous loading doses followed by a constant lidocaine infusion. Patients with ventricular arrhythmia should be treated with direct-current countershock if hemodynamic deterioration is present. Drug therapy for patients with ventricular arrhythmias who are resistant to lidocaine include procainamide, bretylium, or intravenous amiodarone (experimental drug).Treatment of atrioventricular block in acute infarction depends on the site of atrioventricular block, the infarct location, and the hemodynamic status. Generally, atrioventricular block associated with inferior infarction and normal hemodynamic states generally does not require insertion of a pacemaker. In contrast, patients with anterior myocardial infarction and Mobitz II or third degree atrioventricular block should be treated with emergent temporary insertion of a pacemaker. In addition, prophylactic pacing is clearly indicated for those with acute myocardial infarction complicated by the bifascicular block pattern or first degree atrioventricular block and new onset bundle branch block.     

Long-term survival of chronic dialysis patients in comparison to that of stroke and acute myocardial infarction patients

Background. There are no data comparing the long-term survival of chronic dialysis patients with that of acute myocardial infarction (AMI) or stroke patients. We obtained outcome data from two community-based registries, one for dialysis patients and one for patients who suffered an AMI or stroke. Methods. Patients were entered into the registries between April 1, 1988, and March 31, 1991, in Okinawa, Japan. Only patients who survived for 28 days after starting dialysis or after the onset of AMI and stroke were studied. A total of 646 chronic dialysis patients, 747 AMI patients, and 3809 stroke patients were followed up until March 1, 1999. Survival rates were compared between the dialysis patients and those suffering AMI or stroke, based on Cox proportional hazard analysis, and relative risk (95% confidence interval [CI]) of death was estimated after adjusting for sex and age at onset. Results. The relative risk (95% CI) of death for AMI and stroke patients was 0.39 (0.33–0.46) and 0.40 (0.36–0.46), respectively, when the death risk of dialysis patients was taken as reference (1.00). The relative risk for patients with cerebral hemorrhage was 0.44 (0.38–0.50), with the value being 0.40 (0.35–0.46) for patients with cerebral infarction, and 0.37 (0.28–0.49) for those with subarachnoid hemorrhage. Conclusions. Survival in dialysis patients is clearly worse than that in AMI and stroke patients. Specific factors leading to the higher mortality rate in dialysis patients remain to be determined. Received: December 6, 2000 / Accepted: February 15, 2001     

Sudden cardiac death in competitive athletes

Sudden cardiac death in competitive athletes is a rare event in spite of the large numbers participating in organized sports. These tragic episodes usually receive significant media coverage and stimulate intense discussion in the lay and medical communities about how future occurrences might be avoided. This clinical commentary will review a variety of issues concerning sudden cardiac death in competitive athletes, including epidemiology, causes, screening methods, and potential for prevention.     

Clinical predictors of early death in acute myocardial infarction. A prospective study of 233 patients

Patients who suffer acute myocardial infarction are heterogeneous and prognosis differs widely. High-risk patients are likely to derive the greatest benefit from treatment in an intensive care unit and from early thrombolytic therapy. A study was undertaken to determine those clinical parameters, available on admission to hospital, which would predict early death (within the first 30 days) and in this way to define high-risk patients. From July 1985 to December 1987, 233 patients admitted to J. G. Strijdom Hospital with acute myocardial infarction were prospectively evaluated. A total of 30 variables, including clinical, ECG and biochemical parameters, were recorded for each patient on admission. During the study period 36 patients (15.5%) died. The following variables were significantly associated with early mortality: age, Killip class, infarct location, height of ST-segment elevation and raised blood urea level. Using data readily available on admission to hospital, patients at highest risk of early death can be identified.     

Renal insufficiency and anemia are independent risk factors for death among patients with acute myocardial infarction

BACKGROUND: Chronic kidney disease (CKD) increases risk of death among patients with coronary artery disease. Mortality risks associated with CKD among patients with cardiovascular disease (CVD) are not well defined. Anemia is associated with increased mortality in end-stage renal disease (ESRD) patients and may also increase risk among patients with CVD. METHODS: A random sample of patients admitted to the hospital in a single southern state with a principal diagnosis of acute myocardial infarction (ICD-9 codes 410.xx) were followed up after hospital discharge. RESULTS: CKD was found in 60% of the cohort. Hematocrit of >or=40 was found in 46% of the patients; 26.0% had a hematocrit between 36% and 39%, 21.8% between 30% and 35%, and 5.9% had a hematocrit of less than 30%. The 1-year death rates among individuals with and without CKD were 31.7% and 10.4% respectively [odds ratio (OR) = 4.00 (2.34, 6.91)]. The mortality at one year was 18.6% for individuals with a hematocrit greater than or equal to 40%; 23.5% (OR = 1.35; 95% CI = 0.78, 2.32) for hematocrit 36% to 39%; 30.7% (OR = 1.94; 95% CI = 1.12, 3.34) for hematocrit between 30% and 35%; and 35.8% (OR = 3.16; 95% CI = 1.35, 7.40) for those with a hematocrit less than 30% (chi2 for trend was 12.2, P = 0.007). Both hematocrit and serum creatinine were independently associated with increased risk of death during follow-up after controlling for other patient risk factors. CONCLUSION: CKD and decreasing hematocrit were frequent among older patients hospitalized for acute myocardial infarction and are independent predictors of subsequent risk of death.     

Post-resuscitation haemodynamics in a novel acute myocardial infarction cardiac arrest model in the pig

BACKGROUND AND OBJECTIVES: Although a considerable amount of promising experimental research has been performed on cardiopulmonary resuscitation, clinical data indicate an ongoing limited outcome in human beings. One reason for this discrepancy could be that experimental studies use healthy animals whereas most human beings undergoing cardiopulmonary resuscitation suffer from acute or chronic myocardial dysfunction. To overcome this problem, we sought to develop a new model of myocardial infarction, that is easy to perform in all kind of laboratories and compromises on the myocardial function significantly. METHODS: Following approval by the local authorities, 14 domestic pigs were instrumented for measurement of arterial, central venous, left atrial and left ventricular pressures. Myocardial infarction was induced in eight pigs by clipping the circumflex artery close to its origin from the left coronary artery (infarction group; n = 8). Six animals (no infarction group, n = 6) served as no-infarct controls. Following a 4-min period of cardiac arrest, internal cardiac massage was performed in these two groups, and haemodynamics were recorded during the first 30 min of reperfusion. RESULTS: All animals were resuscitated successfully. Compared to the no-infarction group, the infarction group showed significantly decreased myocardial contractility, coronary perfusion pressure and cardiac index (30 min after restoration of spontaneous circulation: infarction group: 57 +/- 7 and 89 +/- 19 mL min-1 kg-1 in the no-infarction group; mean +/- SD; P < 0.05) during reperfusion. Two animals from the infarction group (25%), but none of the animals in the no-infarction group, died during the reperfusion period.CONCLUSION: These data demonstrate that clipping of the circumflex artery leads to a reduced myocardial performance after successful resuscitation, whereas the rate of restoration of spontaneous circulation is not reduced. Therefore, this set-up provides a reproducible model for future studies of post-resuscitation haemodynamics and treatment.     

急性心肌梗死主动脉球囊反搏治疗患者的早期心脏康复

目的 探讨早期心脏康复方案在经主动脉球囊反搏辅助循环治疗急性心肌梗死患者的应用效果。方法选择100例经主动脉球囊反搏辅助治疗的急性心肌梗死患者,随机分成对照组和干预组各50例。对照组给予常规康复训练,干预组在此基础上给予早期心脏康复训练,康复训练内容包括呼吸锻炼、肺部体疗、主动和被动肌力训练,营养支持及心理干预等。结果干预后,干预组血栓栓塞发生率以及疼痛、焦虑及抑郁程度显著低于对照组,日常生活能力评分、左心室射血分数显著优于对照组(均P<0.05)。结论早期心脏康复方案的实施,可促进经主动脉球囊反搏辅助治疗的急性心肌梗死患者康复,减轻焦虑抑郁情绪,提高生活质量。